The Clinical Research Unit (CRU) at Presbyterian Medical Center is being reactivated as a component of the Comprehensive Sickle Cell Center at the Children's Hospital of Philadelphia. In the first cycle of this Center (1988-93), Presbyterian Medical Center was a participating CRU for adult patients. The hospital has been acquired by the University of Pennsylvania Health Systems and has become a member of the Penn family of institutions. The Department of Internal Medicine and the Division of Hematology of the University of Pennsylvania School of Medicine are collaborating with this center to re-establish a sickle cell disease program for adults at Presbyterian. Dr. Eric Russel and his colleagues will maintain a CRU at Presbyterian. The CRU will be the unit through which the participation of adult patients in clinical research studies of the Center will be organized/ The staff of this unit will work closely with the CRU at CHOP to coordinate all joint research activities.